The invention relates generally to contactless power transfer systems and, in particular, to contactless power transfer for subsea applications.
Subsea or other underwater well drilling procedures, such as those used in the oil and gas industry, include use of multiple electrical connections such as, for example, connections between sub-sea distribution units and floating drilling vessels or floating oil platforms. Another example of electrical connection includes coupling between an annular space around a well bore and a tree head within a wellhead to provide power to down hole elements such as sensors. Traditional installation approaches include precisely aligning connections from the tubing hanger to the tree head. Alignment is difficult to achieve in sub-sea environments, particularly in deeper waters and in situations wherein the wellbore is deviated from a vertical position to maximize reservoir penetration into a hydrocarbon bearing structure. Conventional installation approaches additionally involve the use of divers or remotely operated vehicles to effect the physical connection necessary for mechanical connections of electrical contacts between the tubing hanger and the tree and wellheads.
Typically wet-mate connectors are implemented in sub-sea drilling systems to couple two or more elements such as distribution systems, sensors, and electronic modules. Such wet-mate connections require increased isolation from seawater at high pressure while ensuring reliable mating/de-mating operations. Wet-mate connectors implementing mechanical moving contacts are difficult to control and align in sub-sea environments. Another design for coupling between concentric wellhead elements includes an inductive coupler to transfer an electrical signal across two coils aligned in close proximity. However, such a design is unattractive mechanically due to the two coils occupying a large space. Further, such systems have limited bandwidth and lack efficiency when subjected to larger gaps, load variations, or misalignments.
Thus there is a need for solutions having contactless power transfer that will not require precise alignment and will not require a remote operated vehicle or diver for coupling.